To provide good economy and to prevent the wasting of resources by realizing miniaturization and low costs by using a DC motor, and replacing a short-life constituting member.

This centrifugal pump is housed in a cover 2, and provided with an impeller 7 attached to the rotary shaft 6 of a motor 5 using a DC motor, a centrifugal room forming member 11 positioned in the midway of the suction and discharge ports 8 and 9 in a pump casing 10 housing the motor to pressure-feeding fluids from the suction port to the discharge port by the rotation of the impeller housed in the centrifugal room, and the like. In this case, a freely detachable structure is made where the motor is attached/detached from the outside of the pump casing 10, the centrifugal room forming member 11 is attached to the cover 2, and it is removed from the pump casing integrally with the motor, and the motor, the impeller and the centrifugal room forming member are all replaced simultaneously.